Although breast feeding by HIV-infected women is known to increase the risk of mother-child transmission, the culture of breast feeding is not likely to change soon. The relationship between viral load (VL) and transmission is critical and requires careful quantitative studies and systematic and vigorous monitoring of VL in breast milk of women (i) to identify the number of women who constantly shed virus and (ii) to prove the utility of reducing the VL in milk and HIV transmission to babies by a short course of anti-viral drugs. Currently, the routine monitoring of HIV-infected breast feeding women and their infants in developing countries is cost prohibitive and new inexpensive technology for early detection, diagnosis and accurate monitoring of treatment efficacy is necessary. BIOTRACES Inc. has developed a Multiple Photon Detection immunoassay (IA/MPD) for HIV-l p24 protein which is 1,000-fold more sensitive than standard assays. In Phase I, an improved p24 IA/MPD enabled robust quantitation of H1V-l with a sensitivity comparable to current PCR based assays, i.e. sensitivities equivalent to 10 virions per ml. The aim of Phase II is to develop a clinically relevant, ultra high sensitivity, low cost, quantitative p24-based VL assay for use in developing countries. To achieve this, an IA/MPD with a sensitivity of 5 fg per ml or 50 virion per ml, will first be optimized for the detection and quantitation of Clade C p24 and used for measuring (a) VL from breast milk and plasma from treated and untreated African women in Zimbabwe (a HIVNET 023 Study) and Zambia (pending study) (b) for the early detection of very low viral copies in infants born to seropositive mothers. Parallel VL measurements on aliquots of the same samples, using the Roche assay, will allow a direct comparison between the RNA-based and the less expensive p24 -based technology. This assay will also be used for VL testing of HIV-l Clade B-infected individuals as a first step towards a commercially viable assay. PROPOSED COMMERCIAL APPLICATION: Not Available